Comparing Growth Rates of Simulated Moist and Dry Convective Thermals
Comparing Growth Rates of Simulated Moist and Dry Convective Thermals
复制标题
比较模拟潮湿和干燥对流热量的增长率
DOI：
10.1175/jas-d-20-0166.1
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发表时间：
2020
影响因子：
3.1
通讯作者：
S. Sherwood
中科院分区：
文献类型：
--
作者：
H. Morrison;J. Peters;S. Sherwood
对流热气流的传播速率与它们的净夹带有关，以前的文献已经表明潮湿和干燥热气流之间的传播速率存在差异。在这项研究中，理想化的数值模拟的轴对称干和湿对流热气流的增长率进行了直接比较。在干中性层结的环境中，热半径随高度dR/dz的增加是干热气流相对于湿热气流的1.7倍。在距离初始热高度约4个半径范围内的干热气流中，热体积ε的分数变化也更大。dR/dz的值几乎是恒定的高度湿和干热气流符合经典理论的基础上量纲分析。模拟也是一致的理论相关的冲动，流通，并在以前的论文中提出的干热气流的传播速度，并在这里扩展到潮湿的热气流，预测他们将传播小于干热气流。在干热气流中加入加热的试验表明，湿热气流的dR/dz和ε较小，因为潜热主要局限于其核心。附加的轴对称潮湿模拟使用修改后的直减率和大涡模拟支持这一分析。总体而言，这些结果表明，缓慢的传播速度是由潜热加热引起的湿热气流的基本特征，潜热加热改变了相对于干热气流的浮力空间分布。
The spreading rates of convective thermals are linked to their net entrainment, and previous literature has suggested differences in spreading rates between moist and dry thermals. In this study, growth rates of idealized numerically simulated axisymmetric dry and moist convective thermals are directly compared. In an environment with dry-neutral stratification, the increase of thermal radius with height dR/dz is a larger by a factor of 1.7 for dry thermals relative to moist thermals. The fractional change in thermal volume ε is also greater for dry thermals within a distance of ~4 radii from the initial thermal height. Values of dR/dz are nearly constant with height for both moist and dry thermals consistent with classical theory based on dimensional analysis. The simulations are also consistent with theory relating impulse, circulation, and spreading rate for dry thermals proposed in previous papers and extended here to moist thermals, predicting they will spread less than dry thermals. Tests adding heating to dry thermals, either spread uniformly across the thermal volume or concentrated in the inner core, indicate that dR/dz and ε are smaller for moist thermals because latent heating is confined mostly to their cores. Additional axisymmetric moist simulations using modified lapse rates and large-eddy simulations support this analysis. Overall, these results indicate that slow spreading rates are a fundamental feature of moist thermals caused by latent heating that alters the spatial distribution of buoyancy within them relative to dry thermals.
超级细胞是否因其旋转而能抵抗夹带？
影响因子：
3.1
作者：
Peters, John M.;Nowotarski, Christopher J.;Mullendore, Gretchen L.
通讯作者：
Mullendore, Gretchen L.